Vol. 4] Smith. — Upper Region of Bain Walker River. 



1 1 



Professor O. C. Marsh for determination, but only a partial 

 report of their character has been rendered. So far as deter- 

 mined, they include a proboscidian (elephant or mastodon), a 

 horse, an ox, and a camel. The fossils were usually detached and 

 scattered through the sediments, more than one or two bones of 

 the same individual being seldom found at a single locality." 

 This refers to the Quaternary, and the medial gravels referred 

 to are those of the Lahontan beds. The detached occurrence of 

 the fossils is the same as in the case of the Tertiary. The fossils 

 which the writer found were dug from strata tilted about 35°, 

 an amount which is greater than was at any place recognized 

 in the Quaternary. PL 3 shows the amount of tilting. Whether 

 the species are the same in the two instances it is impossible to 

 say, but apparently they are not; and there can be no doubt as 

 to the relative position of the two sets of beds. Professor Rus- 

 sell has mentioned the possibility of fossils being derived from 

 lower beds. However, the amount of their deformation appar- 

 ently is on the side of their being Tertiary. The beds show clearly 

 a gradation of material from fine to coarse. 1 The finer sand- 

 stone shows some sharp grains which may be of volcanic origin. 

 The apparent absence of fossils of an aqueous life might be 

 regarded as an indication of volcanic origin for the whole of 

 such strata, but this for the greater part is not true. 



Specific correlation of the Tertiary beds throughout the Great 

 Basin continues to be on the whole not very satisfactory. Erosion 

 and alluvium isolate and cover them to such a degree that it is 

 impossible to trace them continuously. The value to be placed 

 on their fossil life seems to be somewhat uncertain, with the 

 conclusion of work in each separate region so far investigated. 



The Tertiary and Quaternary. — The unconformity between 

 these is quite sharp. The latter lies very level, and it is mostly 

 obliterated within the area shown on the maps, but in the north- 

 east and northwest corners of Mason Valley lacustrine beds and 

 terraces are preserved. Their thickness, measured in the Walker 

 River Canon is one hundred and sixty feet. 2 



West of the second, or Sing-ats'-e Ridge, and south of the 

 map PI. 1, in Smith Valley, are a few hundred feet of beds which 



1 Bull. Dept. Geol., Univ. Calif., Vol. 2, No. 9. 



2 Mon. XI, XI. S. G. S., p. 141. 



